Various muscles are activated during walking and/or running with the use of traditional footwear. For example, muscles in the lower body of an individual can be activated in response to the repetitive impact forces generated in a gait cycle of the individual wearing traditional footwear. A walker's foot, for example, can experience these impact forces at various points during a typical gait cycle. The gait cycle associated with traditional footwear may begin with the heel strike phase, where the initial ground contact at the lateral side of the heel takes place. The heel strike phase lasts until the rest of the foot or shoe contacts the ground, known as the flat foot phase. In the flat foot phase, the individual's weight rolls forward and inward onto the forefoot as the arch collapses, and moves onto the inner and front part of the forefoot where the foot is pushed off the ground and propelled forward. The flat foot phase lasts until the individual's heel lifts, thereby beginning the toe off phase.